Bio-analytical Approach for Stability Studies of Bendroflumethiazide Materials

In this paper a comprehensive study of stability related, and evidence based best practices of Bio-analytical stability on Bendroflumethiazide drug samples are studied. The proposed approach is very significant and essential for the drugs development process address the specify the acceptancy, purity, efficacy, prediction of strength and quality of the drugs. The stability study constituents several methods like Bench-Top, Auto-sampler, Freeze-Thaw, Dry-extract, Wet-extract, Short-term, long-Term stability studies at relative intervals results the complete stability information about the drug under the proposed and validated method. There ported out comes of this methos shows this drug have good stability according to ICH guidelines.

Relativistic Dynamical Stability Criterion of Multiplanet Systems with a Distant Companion

Multiplanetary systems are prevalent in our Galaxy. The long-term stability of such systems may be disrupted if a distant inclined companion excites the eccentricity and inclination of the inner planets via the eccentric Kozai–Lidov mechanism. However, the star–planet and the planet–planet interactions can help stabilize the system. In this work, we extend the previous stability criterion that only considered the companion–planet and planet–planet interactions by also accounting for short-range forces or effects, specifically, relativistic precession induced by the host star. A general analytical stability criterion is developed for planetary systems with N inner planets and a relatively distant inclined perturber by comparing precession rates of relevant dynamical effects. Furthermore, we demonstrate as examples that in systems with two and three inner planets, the analytical criterion is consistent with numerical simulations using a combination of Gauss’s averaging method and direct N-body integration. Finally, the criterion is applied to observed systems, constraining the orbital parameter space of a possible undiscovered companion. This new stability criterion extends the parameter space in which an inclined companion of multiplanet systems can inhabit.

Bio-Analytical Stability Studies of Nadolol Material

The best practices of Bio-analytical stability studies on drug samples are very crucial and essential for the drugs development process as it specify the acceptancy, purity, efficacy, prediction of strength and quality of the drugs. The main objective of this stability studies on Nadolol the proposed approach of chromatographic separation was administered in isocratic way by using asymmetric C18 column of 40:60 percent of acetonitrile and 0.1% OPA at a flow rate of 1 ml/min is a quantitative measure for drug analysis in biological matrix for more reliable, selective, reproducible and sensitive. This stability study constituents several methods like Bench-Top, Auto-sampler, Freeze-Thaw, Dry-extract, Wet-extract, Short-term, long-Term stability studies at various intervals gave the complete stability information about these drugs. The results of these stability studies are accepted based on ICH guidelines represents this drug has a good stability under the present experimental conditions.

Development and Validation of a Stability-Indicating HPLC Method for the Simultaneous Determination of trans-Resveratrol and cis-Resveratrol in an Injectable Solution

trans-Resveratrol, a phytochemical compound with antioxidant power and various therapeutic effects, such as cardioprotective, chemopreventive, and neuroprotective, among others, has disadvantages of poor solubility and limited stability, creating difficulties for the development of new strategies for its quantification. This study developed and validated an analytical stability method for trans-resveratrol by high-pressure liquid chromatography with photodiode-array detection (HPLC-PDA), which allowed its quantification in the presence of its degradation products. The quantification of trans-resveratrol occurred at a retention time of 2.6 min, with ammonium formate (10 mM, pH = 4)/acetonitrile, 70/30 v/v, as mobile phase. The validation met the ICH Q2 criteria of specificity, method linearity (2.8–4.2 μg/ml), precision and accuracy, robustness, quantification limit (0.176 μg/ml), and detection (0.058 μg/ml). As degradation products, cis-resveratrol was observed at 3.9 min, which could be resveratrone in 3.2 min and five unidentified products in 0.7, 1.0, 1.4, 1.8, and 5 min. Some solutions subjected to temperature stress of 40 and 60°C, UV light, and acidic and basic hydrolysis exhibited colour changes. An analytical method was obtained by HPLC-PDA, which allowed quantifying the stability of trans-resveratrol in a fast and specific manner in the presence of its degradation products.

Competition and Predation Models

The chapter “Competition and Predation Models” considers models with two or more interacting species. What needs to happen for there to be “stable equilibria” that contain all possible members of a system? This is where simple models can be useful: these interactions can be represented by mathematical equations, and then solved for conditions that allow species to coexist. This chapter shows three techniques that make it possible to take a model system and determine whether the system has a stable equilibrium with all members present. The basic principles of model stability are presented, as well as how mathematical models can be used to address basic ecological questions in competition and predator-prey systems. Isocline analysis and analytical stability analysis are explained as ways to predict model behavior and are then used to draw inferences about the processes acting in the real world.

A data-driven model of the COVID-19 spread among interconnected populations: epidemiological and mobility aspects following the lockdown in Italy

An epidemic multi-group model formed by interconnected SEIR-like structures is formulated and used for data fitting to gain insight into the COVID-19 dynamics and into the role of non-pharmaceutical control actions implemented to limit the infection spread since its outbreak in Italy. The single submodels provide a rather accurate description of the COVID-19 evolution in each subpopulation by an extended SEIR model including the class of asymptomatic infectives, which is recognized as a determinant for disease diffusion. The multi-group structure is specifically designed to investigate the effects of the inter-regional mobility restored at the end of the first strong lockdown in Italy (June 3, 2020). In its time-invariant version, the model is shown to enjoy some analytical stability properties which provide significant insights on the efficacy of the implemented control measurements. In order to highlight the impact of human mobility on the disease evolution in Italy between the first and second wave onset, the model is applied to fit real epidemiological data of three geographical macro-areas in the period March–October 2020, including the mass departure for summer holidays. The simulation results are in good agreement with the data, so that the model can represent a useful tool for predicting the effects of the combination of containment measures in triggering future pandemic scenarios. Particularly, the simulation shows that, although the unrestricted mobility alone appears to be insufficient to trigger the second wave, the human transfers were crucial to make uniform the spatial distribution of the infection throughout the country and, combined with the restart of the production, trade, and education activities, determined a time advance of the contagion increase since September 2020.

Unsaturated structured soils: constitutive modelling and stability analyses

The paper presents a new single-surface elasto-plastic model for unsaturated cemented soils, formulated within the critical state soil mechanics framework, which should be considered as an extension to unsaturated conditions of a recently proposed constitutive law for saturated structured soils. The model has been developed with the main purpose of inspecting the mechanical instabilities induced in natural soils by bond degradation resulting from the accumulation of plastic strains and/or the changes in pore saturation. At this scope, the constitutive equations are used to simulate typical geotechnical testing conditions, whose results are then analysed in light of the controllability theory. The results of triaxial tests on an ideal fully saturated cemented soil and on the corresponding unsaturated uncemented one are first discussed, aiming at detecting the evidence of potentially unstable conditions throughout the numerical simulations. This is followed by similar analyses considering the combined effects of both the above features. For each analysed case, a simple analytical stability criterion is proposed and validated against the numerical results, generalizing the results, and highlighting the crucial role of state variables and model parameters on the possible occurrence of failure conditions.

A Data-driven Model of the COVID-19 Spread among Interconnected Populations: Epidemiological and Mobility Aspects Following the Lock-down in Italy

An epidemic multi-group model formed by interconnected SEIR-like structures is formulated and used for data fitting to gain insight into the COVID-19 dynamics and into the role of non-pharmaceutical control actions implemented to limit the infection spread since its outbreak in Italy. The single submodels provide a rather accurate description of the COVID-19 evolution in each subpopulation by an extended SEIR model including the class of asymptomatic infectives, which is recognized as a determinant for disease diffusion. The multi-group structure is specifically designed to investigate the effects of the interregional mobility restored at the end of the first strong lock-down in Italy (June 3, 2020). In its time-invariant version, the model is shown to enjoy some analytical stability properties which provide significant insights on the efficacy of the implemented control measurements. In order to highlight the impact of human mobility on the disease evolution in Italy between the first and second wave onset, the model is applied to fit real epidemiological data of three geographical macro-areas in the period March-October 2020, including the mass departure for summer holidays. The simulation results are in good agreement with the data, so that the model can represent a useful tool for predicting the effects of the combination of containment measures in triggering future pandemic scenarios. Particularly, the simulation shows that, although the unrestricted mobility alone appears to be insufficient to trigger the second wave, the human transfers were crucial to make uniform the spatial distribution of the infection throughout the country and, combined with the restart of (production, trade and education) activities, determined a time advance of the contagion increase (autumn 2020).